The present invention relates to an IC card, an antenna for the IC card, and an antenna frame for the IC card. More particularly, the present invention relates to an IC card having a plane coil formed by punching or etching a thin metallic sheet in which a conductor is wound a plurality of times on the same plane, wherein terminals of the plane coil and electrode terminals of a semiconductor element are electrically connected to each other, and also the present invention relates to an antenna for the IC card composed of the plane coil, and an antenna frame for the IC card.
As shown in FIG. 9, the IC card includes: a rectangular plane coil 100 in which a conductor 102 is wound a plurality of times; and a semiconductor element 104. The above plane coil 100 and the semiconductor element 104 are interposed between two sheets of resin films 106 made of polyvinyl chloride (PVC) on which characters etc. are printed. The two sheets of resin films 106 are made to adhere to, each other by an adhesive layer made of polyurethane resin. This adhesive layer seals the plane coil 100 and the semiconductor element 104.
When the thus formed IC card passes through a magnetic field formed by a card processor, electric power is generated by electromagnetic induction caused in the plane coil 100 of the IC card. Therefore, the semiconductor element 104 is started by the generated electric power, so that communication can be held between the semiconductor element 104 of the IC card and the card processor via the plane coil 100 which functions as an antenna.
The plane coil 100 used for the above IC card is conventionally formed in such a manner that a covered electric wire is wound a plurality of times.
However, when the covered electric wire is wound so as to form the plane coil 100, it is difficult to reduce the cost of the plane coil 100 and also it is difficult to mass-produce the plane coil 100. For the above reasons, it is difficult to spread the use of the IC card widely.
In order to solve the above problems, Japanese Unexamined Patent Publication No. 6-310324 discloses an IC card into which a plane coil, which is formed by punching a thin metallic sheet, is incorporated.
As proposed by the above patent publication, when the plane coil is formed by punching a thin metallic sheet, the manufacturing cost of the IC card can be reduced and the IC card can be mass-produced as compared with the IC card into which the conventional plane coil, which is formed by winding a covered electric wire a plurality of times, is incorporated.
However, it has been found that the handling property of the plane coil formed by punching a thin metallic sheet is very inferior. This is described as follows. When no external forces are given to the rectangular plane coil 100 formed by punching a thin metallic sheet, predetermined intervals are kept between the conductor which is arranged as shown in FIG. 10(a). However, when an external force F acts on the plane coil 100 in the traverse direction as shown in FIG. 10(b), the conductor is deformed, so that the conductor windings, which are adjacent to each other, come into contact with each other, and a short-circuit occurs.
The conductor windings tend to come into contact with each other due to deformation caused by external forces acting on the conductor windings when the plane coil 100 is conveyed and assembled. Also, the conductor windings tend to come into contact with each other by due to deformation caused by the flow of adhesive when the plane coil 100 is interposed between two sheets of resin films 106, on one side of which an adhesive layer is provided.
An object of the present invention is to provide an IC card having a plane coil, the deformation of which is seldom caused by an external force given to the plane coil in the traverse direction when the IC card is conveyed and assembled.
In order to solve the above problems, the present inventors made experiments and found the following knowledge. When a bent portion, which protrudes inward or outward with respect to the plane coil 100, is formed in the conductor 102 on each winding composing a linear portion of the rectangular plane coil 100, it becomes possible to enhance the rigidity of the conductor line 102. Therefore, even if an external force is given to the conductor 102 in the traverse direction, the conductor 102 can sufficiently resist it. According to the above knowledge, the present inventors accomplished the present invention.
The present invention provides an IC card comprising a plane coil formed by punching or etching a thin metallic sheet in which a conductor line is wound a plurality of times on substantially the same plane, wherein terminals at both ends of the plane coil and electrode terminals of a semiconductor element are electrically connected to each other, and a curved portion protruding inward and/or outward with respect to the plane coil is formed in the conductor on each winding composing the plane coil.
Also, the present invention provides an antenna for an IC card having a plane coil formed by punching or etching a thin metallic sheet in which a conductor line is substantially wound a plurality of times on the same plane, wherein a bent portion protruding inward and/or outward with respect to the plane coil is formed in the conductor on each winding composing the plane coil.
Also, the present invention provides an antenna frame for an IC card characterized in that: a plane coil formed by punching or etching a thin metallic sheet in which a conductor line is substantially wound by a plurality of times on the same plane is supported by an outside frame formed in such a manner that a predetermined interval is left between the outermost conductor of the plane coil and the outside frame, and the outermost conductor of the plane coil is connected with a support portion extending from an inside edge of the outside frame.
In the present invention described above, the plane coil is formed into a rectangle, and the curved portion protruding inward and/or outward with respect to the plane coil is formed in the conductor on each winding composing the linear portion of the plane coil. Due to the above structure, rigidity of the conductor can be enhanced. Therefore, it is possible to sufficiently resist an external force given to the plane coil in the transverse direction.
Concerning the curved portion of the conductor on each winding, when the conductor on each winding is curved at the substantially same position in the same direction, it is possible to form a plane coil having the bent portion in which the conductor on each winding is curved.
When an inside frame is formed in a space inside the plane coil in such a manner that a predetermined interval is left between the innermost conductor of the plane coil and the inside frame and also when the innermost conductor is connected with a support portion extending from the outside edge of the inside frame, the space inside the plane coil can be substantially closed by the inside frame. Due to the above structure, when the antenna frame for the IC card is conveyed, it is possible to prevent another antenna frame of the IC card from entering the space inside the plane coil. Therefore, the handling property of the antenna frame of the IC card can be further enhanced.
Further, when the conductors adjacent to each other in the inward and outward direction of the plane coil are connected with each other by connecting pieces, the conductors can be integrated into one body and prevented from collapsing when the antenna frame 40 for the IC card is conveyed. Therefore, the handling property of the antenna frame of the IC card can be further enhanced.
In the plane coil used for the antenna for the IC card of the present invention, the curved portion protruding in the inward and/or outward direction of the plane coil is formed in the conductor on each winding. Therefore, the rigidity of the conductor of the plane coil of the present invention is higher than that of the conductor in which the curved portion is not formed. Further, the rigidity of the plane coil composed of the conductors can be enhanced, since the rigidity of conductor""s is enhanced.
As a result, even if the conductor of the plane coil is given an external force in the traverse direction when the plane coil is conveyed and accommodated in the manufacturing process of the IC card, the plane coil is seldom deformed. Therefore, it is possible to effectively prevent the occurrence of short circuit of the conductor on each winding composing the plane coil used for the antenna. Accordingly, reliability can be enhanced.